Means for protecting electrical circuits.



P. MAOGAHAN.

MEANS FOR PROTECTING ELECTRICAL CIRCUITS. APPLICATION IILEDYJAN. 10, 1908.

7 977,648. Patented Dec. 6, 1910.

2 SHEETB-BHEET l.

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6 @zy IQ BY (QM-o 7 ATTORNEY P. MAGGAHAN- MEANS FOR PROTECTING ELEGTRIGAL OIROUITS.

APPLIGATION rum) JAN. 10, 1908.

977,648. Patented Dec. 6, 1910.

Z SHEETS-SHEET 2.

WITNESSES: 5:. mv NTOR ATTORNEY PAUL I MEANS FOR 1 1103513151? Applicatiomfileti January 19,

""ITED S'IAMIES PATENZT :11, 013 WILKINSHURG, WESTINGHOUSE ELEGTEIG 'i) PI'XTEBUELG', PENNSYLVANIA, A (JQRPORATIQN OLE PENIEYE'LV AY "1 N15 ASSIGIJOR, BY MESNE Spenificatinn of l miters "ma rm/ma vii mm. 'rr'w' concern:

l; it .own firm; 1,, PAUL MACGrM-Iem a inc: United States, and a madam 'nsbltu'g, in the Conny M10 heny "e of Yennsylvmaia, have invmted a ful Imw'oven'ient in. Means Filectric'fl. Circuits, 0f which the .2119; is a specificntiun im'nniiion relates t0 protective Czmices:

' a} distributing ems, pursa'a'lch devises adapted to compr paralbei hailsam iz'xjmf'ieatit-aim I ia'n'ention is pmvi (1e indi 3 in "which me disconmctcfl of the system more i mwerf by in in m-Mn'e the maintenance anfi; refiabfiiiiiy 0i? service rm'lderod, by elemrim i comnmin expen ient 1'10 emplsy in-n lines, and it has here saw 5111*; i0 pmhact a ayziitel'n of that; 11mm the, occurrcmce of 1 injury 0 915a fins it woui become auto- :mtimfl al flomec'ied from the rem mdar 3E M10131? di turbing the other limes! J1 11:25; b u acomplishmi, c-n nnpe however menus-1e even U112 cccmzemre of a short-cirupon one .aim wrmnt will m of Hm ii in the. TQVQZ'FE "on, n11 abnormzfl animuni of "1w 32 111? time, and due i0 a 0 Mn'er Hm: in 15b0,

czws've he iii-Quitprompf! as ins? zmcv, ha l .1 H1012 gh, upon mm: O1?

$1 2110 c 11110 11 stem of p11 tzz-ectin r hm'emfm'e in prim 6%. in Whidk mwfinury ovsrhmd relays 2 dated with piremit-break.s in each Am fine aii film pnwel house, and in are x 1 means movided at each sub-station for opening qircuibbreakers 51: 0M?) 3511; iflmr pm the occmzrence 01 an overload of the {10w of cnergy in B One devic which has hereto Vided for 33).: ailation a; the Sub been profitahon end f upon revel'ani ansmission lines (:0 asktu' 0' mg a circuit in connecc'mt V revmsc", the two torques act in #11 canon, and 1'? H1 2 mm torque @rmined arm Junk, the (16 ice '7 caus the circuit-brcaker 0p .Vhlle the said device supplied the lQH'IflDCi f0 21 1 2y that should operate when the an 0 of an fl-0m a system bOCQI'R S so 12139 as 11g cause a VHF)? n'lm'm'ial z-eductlon in M19 vohzaqe, am} while it may be so '26. 551211; it will operate to cause (he oiz'cuiz-meakers to open whun ciacuit m "a sed by a sma'fimr mmmnt of 122mg in the mverse 0'1? nay-rm (-iimctifin than in 7110. 119.3151 dimciion, when shmrt circuits or law resistnnw grounfw occur 11 a s11b-i hrii n an 11 Cause very low vofii'agges at Hm Sub-QUEHUZ], the (ficvice assuciaied wit :1]! lminjmcfi 1 "my sperms by 11215011 0'? m'crinmz .fiz'n subsizzm'liaiiy sinnflw iwmzsly \Viji'h the o'pmn'inn of HM device :25- socia ME wi'h Hm iHj UQQfiHO which 0pmnos mving g in :1 EOYCISM of the flow of onm'g y. Thu 110%: only the disabled line, but; he mzinjmad lino m; W011}: nay beconw dis- (1i from the rcmni 11601 of the system. Awarding; to the present invsntion, the c5rcnibbi'mkcz's are caused .10 open more 1 y when the circuit is fraversod by the raw (2 of normal dirvction when an ubnornm} amount of current in :1' line for a pre6ern1ined length of lune.

'10 ibis 611d than piiersent sySim'n 1 19 sand device @mployed* of the magnet winding 12. 50'

two switches for governing the operation of circuit in the reverse of normal direction. One switch operated by means of the altiovc-mentioned device invented by Frank Conrad, and the other switch is operated by means of a wattmeter device. To eiiect operation of the CllCUlt-blCillx'Gl'S when the current traversing the circuit exceeds a predetermined amount. a third switch that is connected in shunt to the aforesaid switches is closed by means of a time limit overload device. Thus, by the present arrangement, if a ground or short-circuit occurs upon one of the lines near a sub-station, the circuitbrealters at the substation, in the disabled line, will be operated because of the reversal of the How of energy in that line, while the over-load. in the uninjured line resulting from the injury to the other line will not cause the circuitn'ealrers in the uninjured line to open unless the overload conditions persist for a predetermined length of time.

The accon'ipzmying drawings illustrate diagrammatically systems embodying my invention, that of Figure 1 being a three-phase system and that of Fig. 2 a two-phase system.

The system of Fig. 1 comprises two pa allcl transmission lines 1-23 and et5-6 that feed at a sub-station a suitable distributing circuit 789, multiple-pole circuitbreakers 10 and 11 being interposed respectively in the transmission lines at the sub station.

Each transmission line is protected by a similar system of relays, and it has, there fore, been deemed necessary to illustrate and d scribe completely only the system employed in connection with one of the lines.

The circuit-breaker 1O is'tripped by an electromagnetic device comprising a magnet winding 12 the circuit of which includes a battery 13, or any other suitable source of current, and three pairs of similar switches 14 and 15 that are disposed in parallel circuit and are employed to govern the circuit One pair of the switches 14 and 15 is provided for each phase of the distributing system, and, since the circuit arrangements and the devices provided for each hase are substantially identical, they will e described only with reference to one of the phases. The switch 14 is operated by means of a device 16 constructed substantially like that set forth in Patent- No. 853,218, granted May 14, 1907, to theF/Vestinghouse Electric & Manufacturing Company as assignee of William Bradshaw, except that the-windings are so arranged that the principles, set forth in the above-mentioned application of Frank Conrad n be utilized. The said instrument comp: two-part magnetisable core, the

i core part 20 thereof being provided with a the circuit-breakers in each line, both switches 1 being closed only when energy traverses the winding 21 the energizing current for which is proportional in amount to that traversing line conductor 1 and is supplied by a series transformer 22. The core part 20 is also provided with a winding 23 that is connected in closed circuit with a winding 24 upon core part of the instrument, a voltage being impressed upon the winding 24, which is proportional to that of the transmission line 12 -3, by means of a shunt transformer 26.

The device 16 is actuated, as before explained, by the algebraic sum of twotorques, respectively proportional to the square of current traversing the circuit andto the piednot of the current, voltage and power factor of the circuit, so that the switch 14: will be closed against the action of a spring 27, either when the amount of energy traversing the transmission line 1-2-3 exceeds a predetermined value, or when energy traverses the said line in the reverse of normaldirection. The switch 15 is operated by means of a wattmeter device 28 constructed like that set forth in Patent No. 853,218, current being supplied to winding 29 thereof, which is proportional in amount to that which traverses line conductor 1, by means of the series transformer 22, and to winding 30 thereof, which is proportional in amount to the voltage of one phase of the transmission line 12-3, by means of the shunt transformer The instrument 28 serves to maintain the switch 15 open when energy traverses transmission line 1--23 in the normal direction, and to close the said switch when energy traverses the transmission line 1-2-8 in the reverse of normal direction.- Thus itis seen that both of the switches 14 and 15 are closed only when energy traverses the transmission line in the reverse of nor-, mal direction, and when this occurs, the circuit of the magnet winding 12 is established and the circuit-breaker 10 is caused to open, it being noted that no means are provided for delaying the operations of the devices 16 and 28 and, consequently, a dis abled line will be promptly disconnected at the sub-station end upon a r'eversal'of. the direction of the flow of energy therein.

Connected in shunt to the switches 14 and 15, so as to control the circuit of the magnet winding 12 independently thereof, is another switch 32 that is operated by means of, electro-magnet windings 33, one foreach phase, the energizing currents for which are respectively. proportional in amount to those traversing line conductors 1, 2, and 3, and are sup lied by series transformers 22, 34, and 35,-the-switch 32 -being so delayed in itsoperation by a dash-pot 36, that it may not close upon the occurrence of a sudden overload, but can be closed only when an abnormal amountcf current persists in the traversed by energy in the normal direction, and a third switch for controlling the cir' cuit-breaker-actuating means that is operated only after the circuit has been traversed by an abnormal amount of current for more than a predetermined length of time.

5. The combination with an electrical circuit, circuit-breakers therein, and actuating means for the circuitbreakers, of two switches for controlling the said actuating means, means for closing one of the switches only when the circuit is traversed by ener y in the reverse of normal direction or more than a predetermined amount of current, and means for maintaining the other switch open when the circuit is traversed by energy in the normal direction and for closing it when the circuit is traversed by energy in the reverse of noiinal direction.

6. The combination with an electrical circuit, circuit-breakers therein, and actuating means for the circuit -breakers, of two switches for controlling the said actuating 'means, means for closing one of the switches when the circuit is traversed by energy in the reverse of normal direction, and means for maintaining the other switch open when the circuit is traversed by energy in the normal direction and for closing it when the circuit is traversed by energy in the reverse of normal direction, and a third switch for controlling the circuit-breaker-actuating means that is operated only after the circuit has been traversed by an abnormal amount of current for more than a predetermined length of time.

In testimony whereof, I have hereunto subscribed my name this 23rd day of Dec, 1907.

PAUL MACGAHAN. Witnesses M. C. RYPINSHI, BIRNEY HINES. 

